US3534153A - Color television system - Google Patents

Color television system Download PDF

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US3534153A
US3534153A US614281A US3534153DA US3534153A US 3534153 A US3534153 A US 3534153A US 614281 A US614281 A US 614281A US 3534153D A US3534153D A US 3534153DA US 3534153 A US3534153 A US 3534153A
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color
signal
hue
pulse
amplitude
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Georges Valensi
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/16—Picture reproducers using cathode ray tubes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N11/00—Colour television systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N11/00—Colour television systems
    • H04N11/06—Transmission systems characterised by the manner in which the individual colour picture signal components are combined
    • H04N11/12—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only

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  • two small cathode ray tubes having respectively a white fluorescent screen and a trichrome uorescent screen, produce a detailed black and white picture corresponding to the luminance signal (Y or Y), and a coarse picture in saturated colors corresponding to the hue signal (C)-these two pictures being produced in synchronism by means of a synchronizing device, and being superposed upon a projection screen by means of an optical device located between said fluorescent screens and said projection screen.
  • the present invention concerns an improved color television system as compared to the known systems based on the mapping of a color diagram in sectors related to various colors, such as the system described in French Pat. No. 1,170,895, or in U.S. Pat. No. 2,920,131.
  • the system in accordance with the present invention not only utilizes the information capacity of the transmission channel, connecting the transmitting and receiving stations, much better than the known systems mentioned above, but also aiords a much greater variety of colors in the colored parts of the picture reproduced at the receiving station, and provides moreover the certainty of reproducing in pure white or grey, the colorless elements of the televised scene.
  • FIGS. la and 1b are diagrams showing how, in known color television systems the color-diagram is mapped in sectors related to various chromaticities, a chromaticity being characterized by a group of two parameters, such as the hue and the saturation degree;
  • FIG. 1c is a diagram showing the use of the transmission channel in the color television system according to the invention.
  • FIGS. 2 and 2a illustrate the Newton color circle mapped in .20 useful sectors related to the 20 essential hues corresponding to the conditions of picture viewing at the receiving station, the sector (hatched on the drawing), between the useful sectorsbearing numbers 1 and 20, Ynot being used;
  • FIG. 3 illustrates a first embodiment of the transmitting station of said improved system in accordance with the invention
  • FIGS. 4 and 4a illustrate a second embodiment of said transmitting station
  • FIG. 5 illustrates the receiving station of the mproved system in accordance with the invention
  • FIG. 5a concerns a rst embodiment of the quantizing network (InC) of FIG. 5;
  • FIGS. 6, 6a and, 6b, 6c show another embodiment of said quantizing network; and y FIGS. 6d, 7, 7a and, 7b illustrate a further embodiment of said quantizing network.
  • FIG. 1a reproduces the color triangle of the International Illumination Committee in orthogonal coordinates (xy), as mapped in case of the known color television system described in lFrench Pat. No. 1,170,895, or in U.S. Pat. No. 2,920,131.
  • the central sector corresponds to white; sectors 1, 6, 7, 12, 13, 18, 19, 24 and 25 correspond to colors of low saturation; sectors 2, 5, 8, 11, 14, 17, 20, 23 and 26 correspond to colors of average saturation; and sectors 3, 4, 9, 10, 15, 16, 21, 22 and 27 correspond to colors of high saturation.
  • FIG. 1b reproduces the Newton color circle as mapped in case of the known color television system described in the copending U.S. patent application Ser. No. 428,130, led Jan. 26, 1965, corresponding to the first addition (dated Feb. 5, 1964) of French Pat. No. 1,428,480.
  • the central sector corresponds to white; sectors 1, 3, 51, 7, 9, 11, 13, 15 and 17 correspond to colors of low saturation; sectors 2, 4, 6, 8, 10, 12, 14, 16 and 18 correspond to colors of great saturation; and the symbols have the following signiiicances: PV, violetpurple-PR, red-purple-R, red,-O, orange-J, yellow- VJ, yellowish green-V, green-BV, bluish green (or cyan)-B, blue.
  • the coded chrominance signal characterizing the chromaticity to be reproduced at the receiving station is an electric voltage proportional to the number of the particular sector corresponding to this color in the mapped color-diagram.
  • lthe chromaticity (or color) represented by point C is dened by its hue, which corresponds to the phase (P) of vector related to the reference axis Ox, and by its degree of saturation, which corresponds to the amplitude (a) of vector the center O of the circle corresponding to pure white (which, conventionally, is Illuminant C of the International Illumination Committee).
  • the known color television system based on the mapped color diagrams of FIG. 1a or FIG. 1b, are convenient only for certain industrial applications requiring only a small number of distinct colors for the reproduction of the picture of the televised scene.
  • the Newton color circle is mapped in at least 2O useful sectors corresponding to the 20 essential hues for average viewing conditions in accordance with Munsells work in colorimetry, plus one unused sector, separating the two useful sectors numbered 1 and 20, and shown hatched on FIG. 2.
  • FIG. l-c illustrates schematically how the transmission channel (between the transmitting and receivingy stations) may be used in case of the color television system in accordance with the invention.
  • (psm) is the transmitted sound signal, constituted by a sound-carrier, the frequency of which is modulated by the sounds(s) accompanying the pictures.
  • FIG. 3 shows a rst embodiment of the transmitting station of the color television system in accordance with the present invention, and based on FIG. 2 for chrominance encoding.
  • (Obj) is the objective of the pick-up camera, which comprises 3 cathode ray tubes (TB, TV, TR) receiving, upon their photosensitive targets, through dichroic mirrors (md), three pictures of the televised scene, respectively blue, green and red.
  • These cathode ray tubes produce the primary color signals (B, blue-V, green-R, red), yapplied to the resistor matrix (MR), at the output of which are obtained: the luminance signal and the chrominance components (I and Q) of the American color television system N.T.S.C.
  • Oscillator (like the one described for example on pages 17-82 and 17-83 and illustrated by FIG. 17-56 of the Television Engineering Handbook published by McGraw-Hill Book Co., Inc., New York, in 1957) generates the color carrier (sinewave of frequency pc), amplitude modulated in ⁇ quatrature by the chrominance components (I, Q), by means of modulators (MI, MQ) (which are conventional balanced modulators generating suppressed carrier amplitude modulated waves illustrated, for example, by the FIGS. 17-50 or 17-51 on pages 17- 77 to 17-79 of the above mentioned Television Engineering Handbook), 90 designates a phase shifter inserted between (Gpc) and (MQ) and producing a phase shift of 90 degrees.
  • the modulated signals are applied to a mixer (ml) (which can be constituted by a simple adding circuit), the output of which is a chrominance wave G'r):
  • FIG. 2a shows the phases of the vectors representing various hues (P, purple-R, redl, yellow-V, green, BV, bluish green-and B, blue) with reference to the phase (pc) of the color carrier taken as origin.
  • Vector (sr) corresponds to the color burst transmitted ⁇ at the end of each line synchronizing pulse (t1) in the American color television system (N.T.S.C.).
  • Vectors I and Q correspond to the chrominance components (I, Q) obtained at the output of the resistor matrix (MR) of FIG. 3.
  • FIG. 2 and at FIG. 2a it appears that the unused (hatched) "sector of the color-circle (FIG. 2) corresponds to vector (P) (purple) on FIG.
  • the adjustable phase shifter (dpr) of FIG. 3 serves to compensate this phase shift of 61 degrees, and is inserted between (Gpc) and (DP), which is a phase detector for producing the hue signal (C), as explained hereafter.
  • This voltage (SY) is applied to the first input of a rst electronic divider (DB1) well known from analog computer circuits and described, for example, on page 274 (FIGS. 8-37) of Samuel Seelys Electron-Tube Circuits, second edition, published by the McGraw-Hill Book Co., Inc., New York, in 1958, which simultaneously receives, at its second input, the luminance signal (Y) coming out of resistor matrix (MR).
  • the chrominance wave (Cr) is applied, through amplitude limiter (la), to thelrst input of a conventional phase detector (DP), which receives, at its second input, through adjustable phase shifter (dpr), the color carrier (pc) produced by (Gpc).
  • DP phase detector
  • dpr adjustable phase shifter
  • pc color carrier
  • Gpc color carrier
  • This hue signal (C) goes through amplitude lter (FA), before being applied to amplitude mod- .ulator (MC), which also receives the color carrier (pc)- to produce the chrominance signal (pCm), applied to the so-called channel-transmitting equipment (Etv), which comprises adding circuits to form by addition of the elementary signals ti, t1, sr, Y or Y', pCm and psm a composite video signal and eventually transmitter equipment comprising a carrier generator and modulator for modulating said carrier by this composite signal.
  • Amplitude filter (FA) which can be constituted by a conventional amplitude limiter, i.e. a circuit providing both base and peak clipping, cancels any value of hue signal C, either less than l, or greater than 20, and which would correspond to the unused sector of the color-circle (hatched on FIG. 2).
  • (pel) and (pc2) are electronic gates normally closed, because of the bias voltage (negative) applied to their gating inputs (g1, g2).
  • (peg) is an electronic gate, normally open, but which closes when a positive voltage is applied, to phase or polarity inverter (i), which feeds the gating input (g3) of said gate (pea).
  • hue signal (C) In case of a white or gray part of the televised scene, the hue signal (C) is zero and gates (pel) and (pc2) are closed, whereas gate (pes) is open, and, through it, the luminance signal (Y) reaches the channel transmitting equipment (Etv).
  • hue signal (C) In case of a colored part of the televised scene, hue signal (C) has a positive value (comprised between 1 and 20), which, applied to the gating inputs (g1, g2) of electronic gates (pel) and (pez), overcomes their negative bias voltage, whereas, through phase inverter (i), it closes electronic gate (pea).
  • This signal corresponds to the amount of white light, which, added to alight of a saturated color corresponding to hue-signal (C), would precisely reproduce well the color of the part of the televised scene being scanned at the considered instant. At this instant, the
  • weighted luminance signal (Y) will reach the channel transmitting equipment (Etv), instead of luminance-signal Y.
  • (Gsy) is the generator of synchronizing signals of sync generator of a known type, controlled by the color carrier generator (Gpc), in the following manner.
  • the frequency of the color carrier is:
  • the sync-generator (Gsy), energized by (Gpc), comprises 3 successive frequency dividers (division by 7, then by 7, then by 5) for producing the intermediate frequency (15,750). It comprises also a frequency divider (division by 2) for producing the line frequency (7875), and, finally, three successive frequencydividers (division by 5, then by 9, then by 7) for producing the field frequency (50).
  • the intermediate frequency derived from the generator of color carrier, should be:
  • This equipment receives also the modulated sound carrier (psm) produced by a frequency modulator, not shown on FIG. 3.
  • FIG. 4 shows another embodiment of the transmitting station of the color television system in accordance with the invention, and based on FIG. 2 for chrominance encoding.
  • (TB), (TV), (TR) and (Tbl) are four cathode ray tubes receiving respectively, through objective (Obj) 3 (blue, green and red) pictures of the televised scene, produced through dichroic mirrors (md), upon the photosensitive targets of (TB), (TV), (TR), and one white picture of the televised scene, produced through prism P, upon the photosensitive target of (Tbl).
  • the projection on a vertical plane (at top of FIG. 4a) shows, behind objective (Obj), the prism P illuminating tube (Tbl), and also shows the position occupied by the dichroic mirrors (md).
  • Cathode ray tubes (TB) and (TR) having a horizontal axis, but which are perpendicular to the vertical plane of said projection, are not shown, in order to simplify the drawing.
  • TB three tubes
  • TV three tubes
  • TR dichroic mirrors
  • Tbl cathode ray tube
  • the resistor matrix (MR) derives only the chrominance components (I, Q) from primary color signals (B, V, R), whereas the luminance signal (Y) is obtained directly at the output of tube (Tbl).
  • the voltages (I, Q) amplitude modulate the sine wave of frequency (pc) produced by (Gpc), by means of quadrature amplitude modulator (MQA) which is built up of balanced modulators (MI) and (MQ), color carrier generator (Gpc), phase shifter and mixer (ml) of FIG. 3, for example, and at the output of which the chrominance-wave (Cr) is obtained.
  • This wave is applied, through amplitudelimiter (la), to phase detector (DP), which receives also the color carrier (pc) through adjustable phase shifter (dpr).
  • DP phase detector
  • pc color carrier
  • dpr adjustable phase shifter
  • At the output of (DP) appears the hue signal (C), which goes through amplitude-filter (FA), before reaching amplitude-modulator (MiC), for modulating the color carrier (pc) and so producing the chrominance signal (pCm) transmitted to the receiving station.
  • the chrominance wave (Gr) is also applied to arnplitude detector (DA) to produce an electric voltage (SY) applied to electronic divider (DEI).
  • This divider receives also the luminance signal (Y) coming from tube (Tbl), and it produces, at its output, the saturation signal (S), which is proportional to the degree of saturation of the color to be reproduced at the receiving station, at the considered instant.
  • (PS) on FIG. 4 is an electronic gate which is normally closed, except during the ⁇ scanning of a colored part of the televised scene, because, then, the hue signal (C) (which is positive), overcomes the negative bias of the gating electrode (gs) of said gate (PS).
  • gate (PS) is closed, and the luminance signal (Y) is amplified by a voltage controlled variable gain amplifier (aY) with its maximum gain (Le. with a gain corresponding to a zero voltage applied to its gain control input), before reaching the channel transmitting equipment (not shown on FIG. 4).
  • aY voltage controlled variable gain amplifier
  • the gate (PS) opens (under control of hue signal C, applied to electrode gs), and the saturation signal (S) appearing at its output is applied to the gain control input (ga) of amplifier (ay).
  • the saturation signal (S) is being applied to the gain control input of amplifier (aY) with such a polarity, that its gain is inversely proportional to the instantaneous value S of the saturation signal.
  • FIG. 5 shows one embodiment of the receiving station of the color television system in accordance with the present invention.
  • E1-v is the channel receiving equipment, at the output of which frequency lfilter (FV) separates the video signal from the sound ⁇ signal (psm).
  • FV frequency lfilter
  • Frequency filter (FY) separates the luminance signals (Y or Y) associated with the line synchronizing pulses (t1), the field synchronizing signals (ti) and the color-burst (sr).
  • Frequency filter (FC) separates the chrominance signal, modulated color carrier (pcm), which is applied to the amplitude detector (DmC), at the output of which the hue signal (C) is obtained.
  • the bloc (Asr) is a color burst separator and comprises a narrow band lter tuned to the color carrier frequency (pc), an electronic gate whose signal input is coupled to the output of the narrow band filter and a gating signal generator receiving at its control input (g) the line sync pulses (t1) and feeding the gating input of the gate with gating pulses whose duration corresponds substantially to the back porch of the line sync pulses.
  • (PY) is an electronic gate normally open, whereas (PY) in an electronic gate normally closed, because an appropriate negative bias is applied to its gating electrode (gy).
  • the positive hue signal (C) is, through inverting triode (i), applied to gating electrode (gy) and so closes gate (PY), while it directly opens gate (PY). Therefore luminance signal (Y) cannot reach its amplifier (aY), whereas weighted luminance signal (Y), after having been amplified by amplifier (aY'), reaches the resistor matrix (MR).
  • hue signal (C) does not exist, gate (PY) remains closed, and through gate (PY), which is open, the luminance signal (Y), after amplification by (aY), reaches resistor-matrix (MR).
  • Amplifier (aC) for hue signal (C), and amplifiers (aY) and (aY) for the luminance signal (Y or Y), are voltage controlled variable gain amplifiers, whose gain is a function of the color burst (Sr) amplitude, the color burst being applied to their gain control inputs, in order to automatically compensate for the random time variations of the reference-equivalent of the transmission channel connecting the channel transmitting equipment (Etv, FIG. 3) of the transmitting station with the channel-receiving-equipment (Erv, FIG. 5) of the receiving station.
  • MR and MR are two identical resistor matrixes comprising, (as shown at the left of FIG. 5), 7 resistors (called Rb, Rv, Rr, X and W) which satisfy the following equations:
  • hue signal (C) amplified by (aC)
  • aC amplified by
  • InC quantized level indicator
  • This indicator as explained in the applicants copending U.S. patent application Ser. No. 428,130, filed Ian. 26, 1965 (corresponding to French Pat. No. 1,428,480), comprises 20 groups of two diodes (corresponding to the 20 useful sectors of the Newton color circle of FIG. 2).
  • the diodes of each group are biased by two neighbouring points of a potentiometer comprising a series of resistors energized by a stabilized source of direct current, the diodes of each group being biased through the primary windings of a differential transformer having a ferrite core, (or through the two input resistors of a transistorized differential amplifier).
  • a potentiometer comprising a series of resistors energized by a stabilized source of direct current, the diodes of each group being biased through the primary windings of a differential transformer having a ferrite core, (or through the two input resistors of a transistorized differential amplifier).
  • an electric pulse appears only at the particular output terminal (Si) of the indicator (InC) which corresponds to the particular quantized value of hue signal (C) at that instant.
  • FIG. 5a represents schematically the quantized level indicator (InC) of FIG. 5. Only the output terminals (S4) for blue (B), (S7) for blueish-green (BV), (S10) for green (V), (S12) for yellowish-green (VI), (S14) for yellow (I), (S15) for orange (O), (S17) for red (R), and (S) for red purple (PR), are shown.
  • a field effect transistor (T0) is used for applying hue signal (C) to the input terminal (E) of indicator (InC).
  • Field effect transistors (T1, T2 to T20) are also connected at the various output terminals (S1, S2 S20) of (InC).
  • These transistors acting as pentodes, avoid any reaction of the time variations of the internal impedance of (InC) either towards the source of signal (C), or towards the amplifiers (acb), (acv) (acr), which respectively amplify the voltages (Cb, Cv, Cr) produced at the three terminals (Cb, Cv, Cr) of (InC).
  • These voltages are obtained by means of properly adjusted resistors connected at the output of each field effect transistor (T1 T20), these adjustments corresponding to a decoding chrominance diagram such as the one represented at the bottom of FIG. 6d.
  • These voltages (Cb, Cv, Cr) correspond, for each output terminal (Si) of indicator (IHC), to the relative blue, green, red components of the hue characterized by the corresponding quantized value (Ci) of hue signal (C).
  • these voltages (Cb, CV, Cr), at the outputs of (acb), (acv), (acr) are respectively applied to the Wehnelt cylinders (w-b, wv, wr) of the three electron guns of picture tube (TVT), which are responsible for the production of fluorescent lights of appropriate intensities and respectively blue, green, red, on each part of the fluorescent screen (F1) of said tube.
  • the cathodes (cb, cv, cr), energized by voltages (B, V, R) produced by matrix (MR), and the Wehnelt cylinders (wb, wv, wr), energized by voltages (Cb, Cv, Cr) produced by indicator (InC), cooperate together, in the desired manner, to reproduce, on finorescent screen (F 1), the color and the brightness of said colored element of the televised scene.
  • M is the perforated mask (within tube TVT) in front of the trichrome fluorescent screen (F1) and the 3 electron beams (modulated by the cathodes and Wehnelt cylinders, as explained above) converge through one hole of mask (M) before striking 3 neighboring points on the screen (F1), producing respectively the blue, green and red lights, which, together, produce for the viewer the picture of the corresponding point of the televised scene.
  • FIGS. 6 and 7 show only those portions of two other embodiments of the receiving station (of the color television system in accordance with the invention), which differ from the corresponding portion of FIG. 5, the remainder of said two embodiments not being reproduced on said FIGS. 6 and 7.
  • the indicator comprises only one group of two diodes (D2, D3), associated with a relaxation oscillator (GOR), which produces two synchronous saw-tooth waves (O1, ⁇ O2), at the frequency (pc) of the color carrier, reproduced by the local oscillator I(GpcR) of the receiving station.
  • GOR relaxation oscillator
  • the saw-tooth (O1) is applied to diode (D2) through the primary winding (p1) of the differential transformer (TD) which has a ferrite core.
  • the other saw-tooth (O2) has the same time position as (O1), and is applied to diode (D3) through the other primary winding (p2) of transformer (TD), and through a battery (P) having an electromotive force equal to the standard quantizing step for hue signal (C), and corresponding to the mapping of NeWton-color-circle (FIG. 2).
  • an electric pulse (i) appears at the terminal (S) of secondary winding (s) of differential transformer (TD), only at the instant when the amplitude of the saw-tooth (O1 or O2) coincides (with an approximation equal to quantizing step P) with the Value of the hue signal (C) reproduced, at said instant, at the output of amplier (aC), which is energized by the received chrominance signal (pCm) through amplitude detector (DmC), the gain of amplifier (aC) being automatically controlled by the received color burst (sr), in order to automatically compensate for the random time variations of the channel connecting the receiving station (FIG. 6) to the transmitting station (FIG. 4).
  • PE is an electronic gate which is normally open, but which closes during the short duration (fr) of the falling part of each saw-tooth (O1 or O2).
  • PEB PEV
  • PER are three electronic gates which are normally closed, and which open only when pulse (i), produced by the secondary Winding of (TD), is applied to their respective gating electrodes (gb, gv, gr).
  • gb, gv, gr gating electrodes
  • the line-synchronizing pulse (t1) is applied to difierentiating circuit (der) followed by diode (d), to produce the short pulse (tl), which opens electronic gate (pe), so that the sine wave (os) of frequency (pc), produced by (GpcR), reaches the first input of phase detector (dp), whereas the second input is energized by received colorburst (sr). There is thus produced, at the output of (dp), the correcting signal (sc), acting (through a circuit (ct) having an appropriate time constant) upon the reactance tube (tr) of oscillator (GpcR).
  • the sine wave (os) of period T produced by (GpcR) and so synchronized in phase and frequency, energizes the Schmitt trigger (TR2) which is adjusted at the level 2 shown at the bottom (on the left) of FIG. 6.
  • each pulse I is applied to dilferentiating circuit (Der) followed by diode (Dl), and the short pulses (i), spaced by the period T of the color carrier, obtained at the output of (Dl), synchronize relaxation oscillator (GOR).
  • FIG. 6b shows, at the top, the color triangle of the International Illumination Committee, in rectangular coordinates (x, y), and, at the bottom, the Newton-colorcircle.
  • O in said triangle, and the center C of said circle correspond to white.
  • the spectrum locus within said triangle, and the circumference of said circle are both graduated in millimicrons, the two ends of the spectrum locus (which are also the ends of the purple-line) corresponding to 380 and 700 millimicrons (extremes blue and red monochromatic radiations).
  • Points B, V, R, within the color triangle correspond to the primarycolors (blue, green, red) generally used in color television.
  • PV indicates violet purple-B, blue-BV, cyan--V, green-VI, yellowish green-J, yellow- 0, orange-R, red-PR, red purple.
  • C the spectrum locus
  • the crossing point (M) between OC and VR is generally considered as the center of gravity of two massesone equal to (Lv/yv) applied at point V, and the other equal to (Lr/yr) applied at point R, with (Lv) and (Lr) being the intensities of green light and red light to be mixed together in order to produce the color represented by point M, and which is very similar to the monochromatic (yellowish-green) radiatiton represented by point C.
  • FIG. 6d is, now, hereafter, considered as the oscillogram of one period T of a sequence of positive pulses (having the long shapes of curves Cb, Cv, Cr respectively). Assuming that these pulses (spaced in time, as shown on FIG. 6d, relatively to each other) are applied to the input of electronic gates (PEB), (PEV), (PER) of FIG. 6, the correct values of the electric voltages (Cb, Cv, Cr) corresponding to hue signals (C) will be produced at terminals (Cb, Cv, Cr) of FIG. 6, at each instant when a short pulse (i) is produced at the output (S) of the quantized level indicator, energized by the received chrominance signal (pCm) which is the color carrier amplitude-modulated by said hue signal (C).
  • a Schmitt trigger (TR1) adjusted at the level 1 shown at the bottom on the left of FIG. 6, is energized by sine wave (s) of oscillator (GpcR), and produces the rectangular wave (or) of the same period (T) as the color carrier and which is shown on line 1 of FIG. 6a.
  • This square wave (or) energizes an integrating circuit (Int), producing a triangular wave of period (T), shown on line 2 of FIG. 6a, which is applied in parallel to three pulse-Shapers (CFB), (CFV), (CFR).
  • At the outputs of said pulse-shapers are obtained positive bell-shaped pulses (Cb, Cv, Cr, FIG. 6), reproducing faithfully those having the same designations on FIG. 6d.
  • LRR time-delay circuits producing the delays required for giving, to said bell-shaped pulses (Cb, Cv, Cr, FIG. 6), the same relative time positions as those pulses having the same designations on FIG. 6d.
  • FIG. 6a shows a first type of pulse-Shaper (CF) which could be used for designing the Shapers (CFB), (CFV) and (CFR) of FIG. 6.
  • low-pass frequency filter (Fpb) enlarge the base and rounds the top of the pulse, thus producing a pulse, shown on line 4 (FIG. 6a), in form of a bell, such as pulses Cb, Cv, Cr of FIG. 6d.
  • TD differential transformer with ferrite core
  • a transistorised differential-amplifier could be employed instead of the differential transformer with ferrite core (TD).
  • the two inputs of the amplifier would replace the primary windings of (TD), and the output circuit would replace the secondary winding of (TD).
  • FIG. 7 A rather different electronic circuit, using a different type of pulse-shaped, is shown on FIG. 7, but fulfills the same function as the circuit of FIG. 6.
  • the short positive pulses (i') which synchronize relaxation oscillator (GOR) with the sine wave oscillator (GpcR) are applied, through appropriate pulse delay means (RBl, RB2), (RV1, RVZ) and (RRI, RRZ), to pulse-Shapers (CFB), (CFV), (CFR), of the type illustrated by FIG. 7b.
  • FIG. 7a illustrates the principle of the pulse delay means of FIG. 7
  • FIG. 7b illustrates the principle of the pulse-Shapers of FIG. 7.
  • the short positive pulse (i, of FIG. 7) energizes the monostable vibrator (uvz'), comprising a resistor and a capacitor of such values that, at the output of (uvi), is obtained a rectangular pulse having a duration (r) equal to the desired delay to be produced; this rectangular pulse is applied to a differentiating circuit 12 (defi), followed by a diode (d), in order to finally obtain a short positive pulse retarded by (T) with reference to the input pulse.
  • FIG. 7b represents pulse-Shaper (CFV) of FIG. 7, taken as an example.
  • the pulse to be produced, beyond (CFV) followed by low-pass frequency filter (FpbV) should have the same shape, and the same time position within the period T of the color carrier, as the pulse (Cv) in the oscillogram shown at the bottom of FIG. 6d.
  • the time scale, within a period T ofthe color carrier, is shown at the top of FIG. 6d, the origin (t1) being the end of the pulse (I) produced at the output of diode D1 on FIG. 7, and coinciding with the .starting point (l) of an assumed motion along the circumference of the Newton color circle (FIG. 6b, at the bottom) taking place during every period T of the color carrier.
  • the pulse delay means (RVI) and (RV2) on FIG. 7 are built for producing delays (tvl-tl) and (W2-t1) for any pulse (i') applied at their respective inputs.
  • the short pulses, thus delayed and successively applied to pulse ⁇ Shaper (CFV), are designated (z'vl and i112) on FIGS. 6d, 7 and 7b.
  • these pulses determine the two stable states of the Eccles-Jordan flip-flop labelled (VeJV) on FIG. 7b.
  • This flip-flop produces, at its output, a rectangular pulse having a duration equal to (tvZ-tvl) and shown on the second line at the bottom of FIG. 7b, at the left side (line labelled VejV).
  • (SCV-i-) and (SCV-) represents constant current sources operating at the positive and negative levels labelled respectively (SCV- ⁇ -) and (SCV-) on the third line, at the lower left of FIG. 7b.
  • These' sources may be pentode tubes, or field-effect transistors operating like pentodes, or they may be made of two silicon transistors having a common base, receiving their emitter currents through large resistors connected to positive and negative sources. Instead of large resistors, use could be made of resistors kept constant by means of Zener diodes.
  • the first stable state of flip-flop (VejV), determined by the first input short pulse (ivl), will control the conductivity of the transistor loading capacitor (C) of FIG. 7b in order to produce the ascending part of the positive trapezoidal pulse shown on the fourth line at the bottom of FIG. 7b (at left).
  • the second stable state of flip-flop (VejV), determined by the second input short pulse (z'vz), will control the conductivity of the transistor loading capacitor C, in order to produce the falling part of said trapezoidal positive pulse.
  • (LV) on FIG. 7b represents an amplitude filter limiting the maximum of said ascending part of pulse to the level (LV max) shown at left of said FIG.
  • FIGS. 7 and 7b represent a low-pass frequency filter which rounds the top of the positive trapezoidal pulse, and which enlarges somewhat the ⁇ base of said pulse, in order to finally obtain the desired bell-shaped pulse (Cv) shown in the oscillogram of FIG. 6d.
  • the sequence of pulses Cb, Cv, Cr shown on. FIG. 6d is produced during each period T of the color carrier, pulses Cb reaching terminal (Cb) of FIG. 7 when electronic gate (PEB) opens, whereas pulses Cv and Cr-reach respectively terminals (Cv) and (Cr) when electronic gates (PEV) and (PER) open.
  • a transmitting arrangement comprising:
  • a set of color pickup tubes having means for scanning a scene in a plurality of colors
  • a chrominance signal in- 13l dicative of the color of the scanned-area said chrominance signal including a hue component represenitng the hue as referred to a scale of hus values and a saturation component representing the degree of saturation of color;
  • selector means controlled by said hue signal for establishing a first circuit condition in the substantial absence of a chrominance signal indicating that the scanned area is colorless, and establishing a second circuit condition in the substantial presence of a chrominance signal;
  • transmission means having inputs and including means for transmitting signals applied to its input over a communication link;
  • a receiving arrangement adapted for cooperating with a transmitting arrangement including a communication link, and means for developing hue, luminance, weighted luminance, and chrominance signals, said receiving arrangement comprising:
  • cathode-ray tube means having color control input means and brightness control input means
  • selector means controlled by said hue signal for establishing a first circuit condition in the absence of an effective hue signal and a second circuit condition in the eifectve presence thereof;
  • a color television system comprising in a cooperating combination a transmission assembly and a reception assembly wherein the transmission assembly comprises: a set of color pickup tubes having means for scanning a scene in a plurality of colors;
  • iirst means connected for developing a luminance signal indicative of the degree of brightness of a scanned area of the scene
  • said second means connected for developing a chrominance signal indicative of the color of the scanned area, said chrominance signal including a hue component representing the hue as referred to a scale of hue values and a saturation component representing the degree of saturation of color;
  • third means connected for combining said luminance signaland the saturation component of said chrominance signal for developing a so-called Weighted luminance signal representing said degree of brightness reduced in proportion to said degree of saturation;
  • selector means connected for establishing a iirst circuit condition in the substantial absence of a chrominance signal indicating that the scanned area is colorless, and establishing a second circuit condition in the substantal presence of a chrominance signal;
  • transmission means having inputs and including means for transmitting signals applied to its input over a communcation link;
  • reception assembly comprises:
  • cathode-ray tube means having color control input means and brightness control input means
  • color control means connected for applying the chromatic signal set to said color control input means of the cathode-ray tube means
  • selector means controlled by said hue signal for establishing a iirst circuit condition in the absence of an effective hue signal and a second circuit condition in the effective presence thereof;
  • said second and fourth means comprises:
  • matrix means having inputs connected to said color pickup tubes and having at least two outputs, each producing a chrominance component
  • quadrature modulator means connected to said two outputs of the matrix means for delivering said chrominance signal as an amplitude and phase-modulated signal wherein the amplitude represents the product of saturation-degree and luminance and the phase represents hue;
  • phase detector circuitry for receiving said chrominance signal and delivering a Variable-amplitude sginal representing said hue; and amplitude-modulating circuitry having a modulating input connected to receive said variable amplitude hue signal and delivering an amplitude-modulated color carrier.
  • a transmitting arrangement as claimed in claim 3, wherein said third, combining means comprises:
  • amplitude-detector circuitry for receiving said chrominance signal and delivering a variable-amplitude signal representing said product of saturation-degree and luminance;
  • said third, combining means comprises:
  • amplitude-detector circuitry for receiving said chrominance signal and delivering a variable-amplitude signal representing said product of saturation-degree and luminance;
  • a divider circuit for receiving said product signal and said luminance signal and delivering a variable-ampltude signal representing said saturation-degree;
  • variable-gain means having a signal input 4for receiving said luminance signal and having a gain-varying input for receiving the saturation degree signal from said divider circuit and delivering said weighted luminance signal as representing said luminance signal reduced in strength in proportion to the color saturation degree.
  • a transmitting arrangement as claimed in claim 1, wherein said selector means comprises gating means having a gating control input for receiving said variable-amplitude hue signal so as to establish said first circuit condition when the hue signal amplitude is substantially zero and said second circuit condition when the hue signal amplitude is of a substantial level.
  • variable-gain means for modifying the eifective strength of the set of chromatic component signals as applied from said deriving means to said color control input means
  • variable-gain means connected to the gain-varying input of said variable-gain means for varying the gain thereof in proportion to said weighted-luminance signal in said second circuit condition of said selector means.
  • the means for deriving the set of chromatic component signals comprises a quantizing network having an input receiving the hue signal and a plurality of outputs corresponding in number to the number of quantized hue values, said outputs selectively energizable in accordance with the Value of said received hue signal, and a chrominance-decoding impedance network having a plurality of inputs respectively connected to the outputs of said quantizing network and having a set of outputs corresponding in number to said set of chromatic component signals, said decoding network being predetermined to combine the voltages appearing at the energized outputs of said quantizing network into a set of output signals representing the color components of the received hue signal value.
  • a receiving arrangement as claimed in claim 2, wherein the means for deriving the set of chromatic component signals comprises:
  • amplitude-comparison means for receiving said hue signal and said sawtooth sweep signal and connected to said gating means for enabling the latter to pass said waveforms to the respective channel outputs on substantial agreement between the amplitude levels of said hue signal and sweep signal;
  • channel outputs will deliver respective signals representing the color components of the received :hue signal value.
  • said amplitude comparison means comprises a pair of diodes, means applying said hue signal to corresponding terminals of both diodes, a diierential circuit device connected to the opposite terminals of the diodes and means connecting said sawtooth signal producing means with said device so as to pass to said diodes respective sawtooth waves which are synchronous but differ incrementally in amplitude between each other, the output of said device being connected to said gating means for enabling the latter to pass said waveforms to the respective channel outputs as the two sawtooth waves reach respective amplitude values encompassing the amplitude value of the received hue signal.
  • said cathode-ray tube means comprises a multigun color tube having beam-producing and beamintensity-controlling electrodes associated with each gun thereof, said brightness control input means comprising the beam-producing electrodes of the respective guns, and said color control input means comprising the beam-intensity-controlling electrodes of the respective guns.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Processing Of Color Television Signals (AREA)
US614281A 1966-02-05 1967-02-06 Color television system Expired - Lifetime US3534153A (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
FR48564 1966-02-05
FR54412A FR89781E (fr) 1966-02-05 1966-03-22 Perfectionnement aux dispositifs de codage en télévision en couleurs quantifiées
FR57192A FR89798E (fr) 1966-02-05 1966-04-12 Perfectionnements aux dispositifs de codage en télévision en couleurs quantifiées
FR67828A FR90487E (fr) 1966-02-05 1966-07-01 Perfectionnements aux dispositifs de codage en télévision en couleurs quantifiées
FR95690A FR91879E (fr) 1966-02-05 1967-02-20 Perfectionnements aux dispositifs de codage en télévision en couleurs quantifiées

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US3534153A true US3534153A (en) 1970-10-13

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US614281A Expired - Lifetime US3534153A (en) 1966-02-05 1967-02-06 Color television system

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US (1) US3534153A (es)
BE (1) BE693530A (es)
DE (1) DE1512623A1 (es)
FR (5) FR89781E (es)
GB (1) GB1165241A (es)
NL (1) NL6701735A (es)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5469186A (en) * 1988-07-15 1995-11-21 Pioneer Electronic Corporation Display device with face plate responsive to multiple wave length beams

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2920131A (en) * 1957-02-13 1960-01-05 Valensi Georges Color television systems with coding
US2982811A (en) * 1957-08-12 1961-05-02 Valensi Georges Color television system with coding

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2920131A (en) * 1957-02-13 1960-01-05 Valensi Georges Color television systems with coding
US2982811A (en) * 1957-08-12 1961-05-02 Valensi Georges Color television system with coding

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5469186A (en) * 1988-07-15 1995-11-21 Pioneer Electronic Corporation Display device with face plate responsive to multiple wave length beams

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Publication number Publication date
GB1165241A (en) 1969-09-24
NL6701735A (es) 1967-08-07
DE1512623A1 (de) 1969-04-03
BE693530A (es) 1967-08-02
FR89798E (fr) 1967-08-18
FR89781E (fr) 1967-08-18
FR91879E (fr) 1968-08-23
FR1489034A (es) 1967-11-03
FR90487E (fr) 1967-12-22

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